VM Backups

Assuming you are using ESX/ESXi, it's unlikely if you plug your External USB drive into the server, you will be able to mount it or see the storage.

You might be able to use this storage in a virtual machine if that is suitable?

If you have ESX 4.x, you can try and use VMDirectPath to connect your device:
http://www.petri.co.il/vmware-esxi4-vmdirectpath.htm

If this is ESXi (free version), your b/u options are pretty limited. You can shut down the VM and make a copy manually to your external drive using Veeam FastSCP (free: http://www.veeam.com/vmware-esxi-fastscp.html), your datastore browser, or WinSCP.

What version of ESX or ESXi do you have? Is this a single host? Do you have vCenter?

~coolsport00

see here for USB passtru'

http://vstorage.wordpress.com/2010/07/15/usb-passthrough-in-vsphere-4-1/

http://www.vm-help.com/esx40i/VMDirectPath/USB_Setup.php

What software are you using to Backup the VMs?

Let me clarify...connecting your device would be a 'passthrough' to your VM. It can't be used by your host. There is potentially a soluton you can look at here by fellow expert "ryder0707":
https://www.experts-exchange.com/Software/VMWare/A_2094-Copy-files-to-USB-drive-under-VMware-ESX4-ESXi4-vSphere-console.html

~coolsport00

or you could use VMware Converter to make backups, from a Workstation with your USB External Hard Drive attached.

I am using ESX 4.x, it is licensed as VM Essentials.  It is a single host machine.  I really only need to backup certain files in the VM itself.  Is the easiest way to just hook up the drive to the VM?  Is that called passthrough?

Thanks, both of you had really good info!

Good Luck with connection.

You've had a lot of good input on backing up things, but I want to address another aspect of your question; snapshots.  A snapshot is NOT a backup of a VM; that is a gross misconception.  Here are some notes that I took from a VMWare seminar that better explains what a snapshot is:

A snap shot is a way to preserve a point in time when the VM was running OK before making changes. A snapshot is NOT a way to get a static copy of a VM before making changes.  When you take a snapshot of a VM what happens is that a delta file gets created and the original VMDK file gets converted to a Read-Only file.  There is an active link between the original VMDK file and the new delta file.  Anything that gets written to the VM actually gets written to the delta file.   The correct way to use a snapshot is when you want to make some change to a VM like adding a new app or a patch; something that might damage the guest OS. After you apply the patch or make the change and it’s stable, you should really go into snapshot manager and delete the snapshot which will commit the changes to the original VM, delete the snap, and make the VMDK file RW. The official stance is that you really shouldn’t have more than one snap at a time and that you should not leave them out there for long periods of time. Adding more snaps and leaving them there a long time degrades the performance of the VM.  If the patch or whatever goes badly or for some reason you need to get back to the original unmodified VM, that’s possible as well.  

Thanks for the input on snapshots!  I was mispoken when I said snapshot.  I really meant backup.  And really all I am trying to do is have a backup of particular files in the VM.  Thanks again as this will be useful info in the future!

Yes, I thought you might have used the wrong word.